Oh, but you shouldn't. These are another instance of the "annoying duplicate"
problem that crops up when you combine widely implemented partial sets with
full,
ordered sets, which happened a lot during the design of the Unicode Standard.
Witness GREEK CAPITAL LETTER OMEGA and OHM SYMBOL, or the micro and mu,
Angstrom and A Ring or Kelvin and letter K.

For each you should follow the preferred coding as specified in the Unicode
Standard.

Copyright and Registered do *not* have either canonical or compatibility
mappings
to the set of circled letters. So, use them.

Micro has a compatibility mapping to the greek mu (had it not been for the
fact that
it occurs in 8859, it would have been canonically mapped to its
counterpart, as have
been the OHM and ANGSTROM and KELVIN).

So use the micro sign to remain compatible with 8859.

Don't use Ohm, Kelvin and Angstrom, unless you want to be denormalized.